Background: As thyroid cancer incidence rises, it is increasingly valuable to recognize disparities in treatment and diagnosis. Prior investigations into social determinants of health (SDoH) are limited to pediatric populations or studies looking at single factors such as race or environmental influences. Utilizing the CDC-social vulnerability index and SEER-patient database to assess the amalgamated, real-world influence of varied SDoH and their quantifiable impact on thyroid cancer disparities across the United States. Methods: In a retrospective cohort study, 199,340 adult thyroid cancer patients from 1975 to 2017 were assessed for significant regression trends in months of follow-up/surveillance, survival, late staging, and treatment receipt across thyroid cancer-subtypes with increasing overall social vulnerability, as well as in 15 SDoH variables regarding socioeconomic status, minority-language status, household composition, and housing-transportation across all the U.S. counties while accounting for sociodemographic regional differences. Results: With increasing overall social vulnerability, decreases in months of follow-up were observed with patients with papillary, follicular, medullary, oncocytic, and anaplastic thyroid cancer (p = 0.001). Comparing lowest with highest vulnerability cohorts, relative decreases in months of surveillance ranged from 55.6% (14.5-6.5 months) with anaplastic to 17% (108.6-90.2) with oncocytic. Socioeconomic status vulnerabilities, followed by vulnerabilities in household composition and housing-transportation type, contributed to these overall trends. Similar survival decreases occurred across all thyroid cancer patients, ranging from 55.9% (9.6-4.2) with anaplastic to 28.3% (97-69.5) with oncocytic. Minority-language status vulnerabilities and housing-transportation types largely contributed to these trends. Increasing overall vulnerability was associated with increased odds of advanced staging for papillary (odds ratio [OR] = 1.07 [confidence interval, CI 1.03-1.12]) and decreased odds of indicated treatment via surgery (lowest, medullary: 0.91 [CI 0.84-0.99]), radiation therapy (lowest, anaplastic: 0.88 [CI 0.82-0.93]), and chemotherapy (lowest, oncocytic: 0.81 [CI 0.67-0.98]) were observed. Vulnerabilities in minority-language status and housing-transportation, followed by socioeconomic status vulnerabilities, were differential contributors to these overall vulnerability trends. Conclusions: Our results show significant detriments in thyroid cancer care and prognosis in the United States with increasing overall social vulnerability while identifying which SDoH quantifiably contribute more to disparities in inter-relational, real-world-like contexts.

Ryuji Arimoto

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